苏州岩溶型高岭土矿床的成因及成矿模式

Genesis and Metallogenic Model of Karst-Type kaolin Ore Deposit in Suzhou, Jiangsu Province

苏州高岭土矿床主要成因特征为:矿化围岩为粘土岩及中、酸性火山岩;矿体的形态及展布受印支期风化剥蚀面、岩溶侵蚀起伏面及断裂交汇部、岩溶洞穴的形态等控制;矿石兼具热液蚀变和岩溶地下水淋滤沉积改造的特点;成矿温度一般低于350℃;矿石的氢氧同位素组成反映风化淋滤改造特征明显;矿化蚀变具分带性。依据苏州高岭土的成因特征及其与碳酸盐岩关系密切的成因机制,建立了苏州岩溶型高岭土矿床的理想模式。其成矿过程总括起来就是:构造导致岩浆上侵,岩浆活动又导致热液活动,产生围岩蚀变和高岭土矿的形成,下部大理岩化灰岩中发育的岩溶活动,使矿体经淋滤、改造而进一步富集。矿床按成因差异又可分为两大类,分别为中低温热液蚀变次生再造岩溶型和次生堆积岩溶型。

The formation of Suzhou kaolin deposit in large scale are usually related to the erosion surface of paleo-karst or paleo-caves which are gathering site. The metallogenic model of karst-type kaolin deposit in Suzhou is set up in accordance with the closely genetic relationship between kaolin and carbonate rocks. On the genetic difference, the idea metallogenic model falls into two types i. e. low-to-moderate temperature hy-drothermal alteration associated with secondary recomposed karst-type deposit such as Yangshan and Yangxi deposits; secondary accumulated karst-type deposit such as Yangyanjing ore block of Yangdong. The metallogenic protolith of kaolin is Permian clay rocks contained rich kaolinite and feldspar, and alkali-rich interme-diateracid volcanic rocks as well as hypabyssal rocks. The distribution of kaolin belt is controlled by regional magmatic and tectonic zones and the orefield is controlled by thrusts or paleo-karst erosion surface. The kaolinite formed by the dissolved alkaline and alkaline-earth metals from decomposition of feldsparthic silicates under the action of acidic carbonate or sulfate ions. The ores are characteristic of hydrothermal alteration and leaching reformed sedimentation. And there are limited alteration zoning in wall rocks, in which kaolinization and sericization are indispensable altered phase. Kaolin deposit Metallogenic model Karst Carbonate rock Suzhou